Embodiments of the present specification relate generally to X-ray tubes, and more particularly to a flexible flat emitter in the X-ray tubes.
Typically, an X-ray tube is provided with tube current that heats an emitter in the X-ray tube to emit electrons towards a focal spot in the X-ray tube. In conventional systems, emitters are made of tungsten filament consisting of coiled wires. However, these filament emitters have very less emission area, which results in slow computed tomography (CT) scans or interventional scans. Also, as these emitters have small area, the emitters may heat up to a very high temperature during operation. As a consequence, the emitters may have very high evaporation rate that may physically damage the emitters and/or the X-ray tube.
In other conventional systems, thermionic flat emitters are employed in the X-ray tube for emitting the electrons. The thermionic flat emitters are more convenient to provide a larger emission area than traditional filament emitters. The thermionic flat emitters include emission segments that are separated by slots. Also, the area of flat emitters may be easily increased compared to the filament emitters. As a result, the temperature of the flat emitters is lower than the temperature of the filament emitters for similar amount of emission, and as a consequence the evaporation rate of the material of the flat emitters is less in comparison to that of the material of the filament emitters. Therefore, the flat emitters have an excellent life advantage. However, thermal cyclic deformation of the flat emitters is a challenge due to higher stiffness in the flat emitters. Particularly, when the emitters are subjected to cyclic thermal loading, it is often observed that the flat emitters exhibit lower flexibility as compared to the filament emitters. Due to lower flexibility, the flat emitters tend to distort/deform permanently over a period of time. Also, this deformation in the flat emitters may cause the flat emitters to lose their original shape and flatness. As a consequence, the focal spot quality of the flat emitters in the X-ray tube may degrade over a period of time.